Field of the Invention
The invention relates to a correction method, and more particularly to a gamma correction method.
Description of Related Art
In conventional displays, such as liquid crystal display (LCD), the adjustment of gamma curves and gamma reference voltages is executed by adjusting gray level voltages of displays to satisfy the standard gamma curve (e.g. gamma curve 2.2), while the displays are lighted up with white frames. In such a way, the displays would show the expected gray levels. However, for displaying pure color frames such as red frames, green frames, and blue frames, the displayed gray levels are much poorer than that of the white frame.
FIG. 1 illustrates gamma curves of the conventional displays. Referring to FIG. 1, the horizontal axis indicates gray levels, and the vertical axis indicates reflectance. The heavy line is the standard gamma curve 2.2, and the gamma voltages of the displays are adjusted based on the standard gamma curve 2.2 when the displays are lighted up with the white frames. On the other hand, the gamma curves of pure color frames could be obtained by optical measurement when the displays are lighted up the pure color frames. The three dashed curves shown in FIG. 1 are the gamma curves of pure color frames. It could be found that there are much offsets between the gamma curves of pure color frames and the standard gamma curve 2.2. As a result, the image quality is poor, and some issues such as poor color and contour effect are induced. In order to improve image quality, a suitable gamma correction method is necessary.